Replaceable annular gear

ABSTRACT

Worn teeth in a shifting transmission are replaced by an annular replacement gear which is slipped over the worn teeth after they have been ground down to a smooth annulus. The teeth of the annular replacement gear are longer than the worn teeth that they replace.

United States Patent [1 1 Liberty, Jr.

[ REPLACEABLE ANNULAR GEAR [76] Inventor: Joseph C. Liberty, Jr., 4216Grindley Place, Dearborn Heights, Mich. 48125 22 Filed: July 30, 1971 21Appl. No 167,640

[52] US. Cl. 192/67 R, 192/4891, 192/108,

[51] Int. Cl. Fl6d ll/l0, B21d 53/28 [58] Field of Search 192/4891, 67R, 192/108, 114 T; 74/446, 447; 29/1592, 401

[56] References Cited UNITED STATES PATENTS 2,125,526 8/1938 Trimbath192/67 R X June 19, 1973 2,832,234 4/1958 Sinclair 192/67 R X 3,219,16411/1965 Henyon 192/114 T 3,083,585 4/1963 Dawe et a1. 74/243 3,230,6161/1966 .lanssen 29/401 3,490,132 1/1970 29/401 Kosters et al..

Primary Examiner-Allan D. Herrmann Attorney-Allan J. Murray [57]ABSTRACT Worn teeth in a'shifting transmission are replaced by anannular replacement gear which is slipped over the worn teeth after theyhave been ground down to a smooth annulus. The teeth of the annularreplacement gear are longer than the worn teeth that they replace.

2 Claims, 7 Drawing Figures PATENEnJumma I 3.739.892

slut-1 or 2 INVENTOR JOSEPH C. L/BE/PTY JR.

ATTORNEY PATENIEU smzurz FlG.5

FIG-4 INVENTOR JOSEPH 6. A 09597) JP.

Mq/M

A TTORNEYS 1 REPLACEABLE ANNULAR GEAR FIELD OF INVENTION BACKGROUND OFINVENTION In the conventional manually shifted form of automobiletransmission, it is common to form, integrally on one hub, two annulargears, spaced apart on said hub,

and frequently of substantially different diameters and toothdimensions. Said hub is rotatablymounted on a drive shaft, and commonlyis flanked by snap rings to resist movement of the hub longitudinally ofthe shaft. Of this dual gear (hereinafter called the driving gear) thelarger gear receives a constant drive during operation of an automobile,as from a cluster gear on a countershaft (not shown).

Said constant drive serves merely to rotate the gear freely on the driveshaft, until it is interconected with the drive shaft by a synchronizerassembly. Such synchronizer assembly is disposed on the drive shaftadjacent to the driven gear, and may include an interiorly splinedclutch hubmounted upon a splined portion of the drive shaft to transmita positive drive to the drive shaft. The exterior circumferentialsurface of the clutch hub is formed with a set of gear teeth. Mountedupon said exterior circumferential surface is an annular sleeve gear(hereinafter referred to as the driven gear) having its interiordiameter formed with teeth which mesh with the clutch hub teeth. Theengagement of the driven gear upon the clutch hub is such that thedriven gear is afforded reciprocable sliding travel on said hub, so thatit may he slid, as by a shifting fork, to telescopically engage itsinterior gear teeth with the second, smaller set of gear teeth on saiddriving gear. It may now be apparent, that the last described engagementcompletes a positive drive from the driving gear through the driven gearto the clutch hub, and thence to the drive shaft. (The terms first andsecond gear are usedonly to distinguish the two gears on the drivinggear, and do not refer to first, second, and third gear speeds of aconventional transmission).

To facilitate shifting, which is the engagement or disengagement of thedriven gear with the said second gear of the driving gear, it has beencustomary to complete the synchronizer assembly with a ring, usuallymade of brass, having some slight floating travel longitudinally of thedrive shaft. As illustrated in a rather elementary manner in thedrawings, and particularly in FIGS. 1, 2, and 3, the circumferentialextent of the clutch hub gear is interrupted by three radially, equallyspaced notches, and the brass ring is further provided withcorresponding notches, so that a key may interengage the brass ring withthe clutch hub and still afford the necessary floating traveLlt maybenoted, again as illustrated in FIGS. land 2, that a portion of the hubof the drive gear is tapered to form a truncated cone, upon which thebrass ring frictionally engages to receive an initial drive whichisintended to bring the speed of rotation of the driven gear to a speedcorresponding to that of the driving gear prior to the engagement of theaforesaid interior teeth of said driven gear with said second gearon thedriving gear.

In the sport of racing stock cars, to further facilitate the speed withwhich a transmission may be shifted from one gear to another, it hasbeen a popular custom to remove, as by grinding, a desired number ofteeth from the interior of the driven gear, and to remove from thesecond gear on the driving gear, a corresponding number of teeth. Thispractice affords the elimination of the above described brass ring aswell as the keys, and spring wire clips (not shown) which retain thekeys in assembly. The greater spacing between the remaining teeth on theinterior of the driven gear, and the teeth of said second gear of thedriving gear, affords greater ease of shifting without the need of thesynchronizing ring, and of course, the fewer the number of teethremaining on the engaging gears, the faster and easier it is to engagethe gears to transmit a drive to the drive shaft.

A further consequence of this custom is, however, that the driven gearengages a rotating driving gear without the benefit of the synchronizer,and as the speeds of the two gears may be considerably disparate,theremaining gear teeth in both gears are subjected to substantialimpact upon engagement. Consequently the second gear on the drivinggear, once it is altered in the aforesaid manner, may last for only 25races(for example) before the teeth on said second gear are so worn andbroken as to require replacement of the gear.

SUMMARY AND OBJECT OF THE INVENTION Improvement resides in the repair,and the method of repair and improvement, of a driving gear comprising ahub rotatably mountable upon a drive shaft, and formed with a firstannular gear spaced from a second annular gear, the second annular gearbeing of smaller overall diameter than the first gear, and having teethof substantially smaller dimensions, and consequently more subject tobreakage and wear; repair is effected by grinding or otherwise removingthe worn gear teeth of the second gear to leave an annular surface ofpredetermined diameter intersecting the plane of the adjacent lateralface of said first gear and applying on said annular surface, anannulus, having an interior diameter corresponding to said annularsurface, and having I a desired, predetermined number of teeth upon itsexterior circumferential surface, and securing the annulus in place asby tack welding, or any other convenient means; the width of saidannulus is such that one lateral face thereof abuts said adjacentlateral face of said'first gear, and the opposite lateral face of saidannulus occupies. a plane approximately one-sixteenth of an inch fromthe opposing lateral face of said driven gear, whereby the gear teeth ofthe annulus are substantially longer and stronger than the worn teeththey replace. Further a metal of superior shock resistantcharacteristics can be employed in the annulus. Thus the best materialscan be selected for both the driving gear and the annulus.

An object of the invention is to provide an economical and improvedgear, and method of repairing and improving said gear to replace wornteeth with teeth of greater width, and consequently of greater strength.

This and various other objects are attained by the invention hereinafterdescribed and illustrated in the accompanying drawings, wherein:

FIG. 1 is an elevational view in partial section taken on line 1-1 ofFIG. 2, of a dual gear rotatably mounted upon a drive shaft, and havinglongitudinally adjacent thereon a synchronizer assembly, of which thesleeve, or driven, gear is portrayed in a neutral position wherein nodrive is transmitted from the driving gear through the synchronizingassembly.

FIG. 2 is an elevational end view of the gears taken on line 2-2 of FIG.1.

FIG. 3 is a view similar to FIG. 1, but with the synchronizer sleevegear shown in engagement with the second gear of the driving gear toreceive a drive therefrom and transmit said drive through the clutch hubto the drive shaft.

FIG. 4 is a view similar to FIGS. 1, and 3, illustrating the modifiedform of the driving gear, and of the driven gear with a number of teethremoved from each, and with the brass synchronizing ring and the keysalso eliminated from the assembly.

FIG. 5 is a vertical, elevational view on line 5-5 of FIG. 4, with theclutch hub removed, to more clearly illustrate the results of removal ofgear teeth in the manner aforesaid on both the second gear of saiddriving gear, and on the interior gear of said driven gear.

FIG. 6 is a view similar to FIGS. 1, 3, and 4, illustrating the drivinggear with all of the worn or broken teeth ground away, and replaced bythe aforesaid specially prepared annulus, or ring gear.

FIG. 7 is an elevational end view of the improved driving gear showingthe annulus (with the new gear teeth thereon) attached to said annularsurface, as such view might appear if taken on line 7-7 of FIG. 6, but

omitting the clutch hub and sleeve gear for clarity.

In these views the reference character 1 designates a drive shaft of anautomobile transmission, said shaft being shown in phantom line to avoidobscuring of the hereinafter described features. A hub 2 is rotatablyreceived upon the shaft, being formed with a hole 3 for this purpose,with a first, larger gear 4, and a second gear 5, of smaller diameter.Said gears are spaced apart axially of said sleeve by a groove 6, whichexists mainly due to the exigencies of manufacture, as it would bedifficult and expensive to machine the teeth in the smaller ler secondgear so that they would intersect the plane of the adjacent lateral face7 of the larger first gear 4. (The terms first and second gear are usedmerely to distinguish the two gears on the dual gear and are withoutreference to the various speed gears in transmission). The gear 3receives a constant drive (not shown) as from a gear mounted on acountershaft, as is conventional in automotive transmissions. The hub 2terminates in an exterior tapered cone.

As the large gear 4 is subjected to a continual drive, but rotatesfreely upon the shaft, naturally, some means is required to transmitsaid drive, when desired, to the drive shaft.,This is effected by theprovision of the clutch hub 9 formed with a hole 10 whereon it isrigidly secured to the drive shaft, frequently as by splines 11. Theclutch hub is formed with an exterior, annular set of gear teeth 12,which is interrupted by slots 13.'I(eys 14 are received in said slots,and have an end portion engaged in a notch 15 in synchronizing ring 16.The synchronizing ring is formed with gear teeth 17 which correspond insize to the teeth of the small gear 5.

Mounted upon the clutch hub 9, is a sleeve gear 19 formed with anannular groove 20 which may receive a shifting fork 21 shown in phantomline. Said sleeve gear may incorporate external gear teeth 22, and isalways formed with internal gear teeth 23 to slidably mesh with theteeth 12 of the clutch hub 9. In some versions of the above describeddevice, the keys are stamped from sheet metal and are formed with thedetent 24 which is received in detent notches 25 formed in the interiorgear teeth 22 on the sleeve gear 19. The detent serves initially tocarry the key in the direction of sliding travel effected by theshifting fork 21. A circular hole 26 on the synchronizing ring 16engages the surface of the cone 8, and a frictional drive is transmittedto the sleeve gear 19, and from thence to the clutch hub 9, and to thedrive shaft 1, to bring rotative travel of the sleeve gear matching thatof the driven gear, to facilitate meashing of the interior teeth 23 ofthe sleeve gear with the teeth of the small gear 5 formed on the hub 9,as illustrated in FIG. 3.

As stated earlier, and as illustrated in FIGS. 4 and 5, i

for racing purposes, a predetermined number of teeth are removed, as bygrinding as shown at 27 on the small gear, and a corresponding number ofteeth are removed, as designated at 28, from the interior gear teeth 22of the sliding sleeve gear 19. As aforesaid, this measureaffordselimination of the synchronizing ring 16, of the keys 14, and ofkey retaining springs (not shown). While this provision affords fastershifting, which is of considerable importance in the sport of racingstock cars, as stated earlier, it imposes a rather short life span onthe remaining teeth, and this is particularly true of the relativelysmall teeth on the small gear 5.

Past practice has been to replace the gear 2, 4, 5 with a new gear whenthe teeth of the small gear 5 are deteriorated beyond useful function,but again, the number of teeth would be ground away from the new gear 5of the replacement gear, and again, the life span of the gear isshortened.

It has been determined that the life of gear 2, 4, 5 may be extendedsubstantially, by the measure of grinding away the worn and broken teethof the gear 5, it being desired to also remove an amount of metal fromthe hub to produce an annular surface 29. It is to be noted that theannular surface intersects the adjacent lateral face 7 of the largergear 4. An annulus 30 is then prepared, having an interior diameter 31corresponding to that of the annular surface 29, which annulus is thenfitted upon said annular surface, and may be secured in position as bytack welding or by any other such means which will afford its subsequentremoval. A desired number of teeth 32, corresponding to the number ofinterior gear teeth 23 remaining on the sleeve gear 19, are formed onthe exterior circumference of the annulus, to replace the broken andworn teeth of the small gear 5, which were removed.

It is a decided advantage on the improved gear that the length of thegear teeth 32 can extend for the full width of the annular surface 29,and may abut the aforesaid adjacent lateral face 7 of the large gear 4,as this greater length also gives the teeth greater strength, andconsequently gives the gear a longer life after the addition of theannulus 30, than it would have had subsequent to its modification tofacilitate shifting, but prior to the addition of said annulus.

A further, and important feature of the invention is the provision, asat 34, of an angular surface ground on the end of each tooth 32 toeffect a camming action when the teeth engage with the correspondingteeth of the sleeve gear 19. As may be perceived, such camming actionwould facilitate engaging the said corresponding teeth, and would go fartoward having such teeth engage smoothly as they intermesh, to reducethe shock, and consequently, wear and destruction of the teeth on thenewly applied annulus.

What I claim is:

l. A power transmission device, including,

a drive shaft,

a driving gear having an annular hub, rotatably mounted on said driveshaft,

a first annular gear integral with said annular hub,

at least one plane, annular, lateral face, formed on said first annulargear, concentric therewith,

a clutch rigidly secured upon said shaft adjacent to said annular hub,and having an exterior, circumferential surface,

exterior gear teeth formed on said circumferential surface, and

a drivable, annular sleeve gear mounted on said clutch hub and havinginteriorly formed gear teeth to mesh in axially slideable engagementwith said exterior teeth, whereby a drive may be transmitted from saidsleeve gear through said clutch hub to said shaft, of

a second annular gear carried by said annular hub to transmit a drive tosaid annular sleeve gear,

said second annular gear having teeth formed of an annulus, havingopposite parallel side surfaces, and having a predetermined interiordiameter, the

length of said teeth extending the width of said annulus,

an annular surface formed on said annular hub and extending axially andtransversely to, and intersecting, said lateral face of said firstannular gear, said annular surface rigidly receiving said annulus, and

said annulus being disposed to abut one said parallel side surfaceagainst said lateral face of said first annular gear, so that one endface of each tooth abuts said lateral face, and

said sleeve gear having at least one plane lateral face and beingaxially slideable on said clutch hub to engage said interiorly formedgear teeth with said teeth of said annulus, and to abut said lastmentioned lateral face against said first mentioned lateral face wherebyto engage the full length of said teeth of said annulus, and to resistfurther sliding travel of said clutch hub. 2. The method of replacing anannular set of teeth on a gear, wherein said gear includes a hub with afirst annular gear formed thereon, said first annular gear having atleast one plane, lateral, annular face, and a second gear formed on saidhub of smaller diameter than said first gear, and spaced therefrom by anannular groove, and wherein said smaller diameter gear is formed withteeth of smaller dimensions than said first annular gear, and subject torapid wear, said method including the steps of removing the worn teethof the second gear in such a manner as to provide an annular surface ofpredetermined diameter, formed to intersect with said lateral face,forming an annulus having an interior diameter corresponding to andreceivable upon said annular surface, and having opposite lateral faces,securing said annulus in a desired position on said annular surface sothat one lateral face of said annulus abuts said lateral face of saidgear, and the opposite lateral face of said annulus occupies a planeoutwardly of the corresponding lateral face of the removed worn teeth,and forming on the exterior surface of said annulus a predeterminednumber of gear teeth of predetermined dimensions, the length of saidgear teeth extending the width of said annulus.

1. A power transmission device, including, a drive shaft, a driving gearhaving an annular hub, rotatably mounted on said drive shaft, a firstannular gear integral with said annular hub, at least one plane,annular, lateral face, formed on said first annular gear, concentrictherewith, a clutch rigidly secured upon said shaft adjacent to saidannular hub, and having an exterior, circumferential surface, exteriorgear teeth formed on said circumferential surface, and a drivable,annular sleeve gear mounted on said clutch hub and having interiorlyformed gear teeth to mesh in axially slideable engagement with saidexterior teeth, whereby a drive may be transmitted from said sleeve gearthrough said clutch hub to said shaft, of a second annular gear carriedby said annular hub to transmit a drive to said annular sleeve gear,said second annular gear having teeth formed of an annulus, havingopposite parallel side surfaces, and having a predetermined interiordiameter, the length of said teeth extending the width of said annulus,an annular sUrface formed on said annular hub and extending axially andtransversely to, and intersecting, said lateral face of said firstannular gear, said annular surface rigidly receiving said annulus, andsaid annulus being disposed to abut one said parallel side surfaceagainst said lateral face of said first annular gear, so that one endface of each tooth abuts said lateral face, and said sleeve gear havingat least one plane lateral face and being axially slideable on saidclutch hub to engage said interiorly formed gear teeth with said teethof said annulus, and to abut said last mentioned lateral face againstsaid first mentioned lateral face whereby to engage the full length ofsaid teeth of said annulus, and to resist further sliding travel of saidclutch hub.
 2. The method of replacing an annular set of teeth on agear, wherein said gear includes a hub with a first annular gear formedthereon, said first annular gear having at least one plane, lateral,annular face, and a second gear formed on said hub of smaller diameterthan said first gear, and spaced therefrom by an annular groove, andwherein said smaller diameter gear is formed with teeth of smallerdimensions than said first annular gear, and subject to rapid wear, saidmethod including the steps of removing the worn teeth of the second gearin such a manner as to provide an annular surface of predetermineddiameter, formed to intersect with said lateral face, forming an annulushaving an interior diameter corresponding to and receivable upon saidannular surface, and having opposite lateral faces, securing saidannulus in a desired position on said annular surface so that onelateral face of said annulus abuts said lateral face of said gear, andthe opposite lateral face of said annulus occupies a plane outwardly ofthe corresponding lateral face of the removed worn teeth, and forming onthe exterior surface of said annulus a predetermined number of gearteeth of predetermined dimensions, the length of said gear teethextending the width of said annulus.